Functional classification is the "process by which streets and highways are grouped into classes, or systems, according to the character of service they are intended to provide." In basic terms, a road can be functionally classified as:
The Federal Highway Administration requires states to classify all public roads per 23 CFR, Part 470 – Highway Systems. They also have a manual that provides guidance on the concepts, criteria and procedures for states to follow. See Highway Functional Classification –Concepts, Criteria and Procedures.
Circumstances in which a road's functional classification is taken into account include:
In Alaska, Federal Highway Administration (FHWA) funds can be used on any public roadway (regardless of the road's functional classification). Road ownership and the state assigned federal functional classification determine which roadways are eligible for the following programs:
The state assigned federal functional classification is one of many factors that are considered when evaluating projects for Statewide Transportation Improvement Program (STIP) funding. For more information about the STIP and funding, please visit ADOT&PF's STIP website
A "public road" is any road under the jurisdiction of and maintained by a public authority and "open to public travel." This could range from a logging road to a multi-lane freeway. "Open to public travel" means that the road is available, except during scheduled periods (including seasonal closures), extreme weather, or emergency conditions; passable by standard passenger cars; and open to the general public for use without restrictive gates, prohibitive signs, or regulation other than restrictions based on size, weight, or class of registration.
The functional classification establishes the engineering standards for design. An inappropriate functional classification can result in roadways built to standards not required by the actual service of the facility.